                     lessonsMap)]
 
         (doseq [moduleInfo newModInfoSeq]
-          (add-module-lesson-group (:moduleCode moduleInfo)
-                                   (:lessonType moduleInfo)
-                                   (:lessonGroup moduleInfo)
-                                   bgColorCssClass
-                                   true))
+          (add-module-lesson-group! (:moduleCode moduleInfo)
+                                    (:lessonType moduleInfo)
+                                    (:lessonGroup moduleInfo)
+                                    bgColorCssClass
+                                    true))
 
         ; Update URL hash with newly added module
         (update-document-location-hash-with-new-module!

            (update-ModulesSelected-for-affected-days affectedDaysSet)

            ; add the newly selected lesson group
            (add-module-lesson-group moduleCode lessonType destLessonGroup
                                     bgColorCssClass true)

            (update-document-location-hash-with-changed-lesson-group!
              moduleCode lessonType destLessonGroup))))))

  Lessons-Created-By-Draggable nil)

; Forward declaration
(declare add-module-lesson-group!)
(declare timetable-prune-empty-rows)
(declare add-missing-td-elements-replacing-lesson)
(declare remove-lesson-group-html)
